Torsion damping device

ABSTRACT

A torsion damping device provided with an associated friction device. The torsion damping device includes a washer (60) frictionally engaging a disk (11) under axial action of spring lugs (63) bearing on a guiding washer (12B). The washer has a substantially annular shape and acts radially beyond an elastic damping member (15, 15a).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a torsion damping device of the typehaving at least two coaxial parts, mounted rotatably in relation to oneanother, counter to elastic damping means generally interposedcircumferentially between them. Such a torsion damping device can beapplied to a friction clutch, notably for a motor vehicle. The inventionmore particularly concerns a friction device acting between the coaxialparts.

2. Description of the Prior Art

In a known torsion damping device one of the rotary parts carries afriction disc, designed to be fixed with respect to rotation to a firstshaft, in practice a driving shaft, the crankshaft of the engine in thecase of an application to a motor vehicle, whilst another of the saidrotary parts has a hub by means of which it is designed to be fixed withrespect to rotation to a second shaft, in practice a driven shaft, theinput shaft of a gearbox in the case of such a motor vehicle.

In such an assembly, the use of at least three rotary coaxial parts, oneof these comprising a hub disc, is also known.

The damping device acts between this rotary part and that fixed to thedriving shaft. The delimitation of the angular movement between thisrotary part and that fixed to the driven shaft is provided by engagementmeans of meshing with clearance. A sub-assembly for preliminarytorsional damping is generally interposed between these latter tworotary parts.

The interposing of an axially acting friction device between two rotarycoaxial parts is also known. Such a device generally comprises afriction washer, one active surface of which rubs against one of therotary parts, and elastic loading means axially forcing the frictionwasher towards the rotary part whilst bearing on the other rotary part.

In the known device mentioned above with three coaxial parts, twofriction devices of this type are generally disposed, one, correspondingto the damper, between the rotary part connected to the driving shaftand the hub disc, and the other, corresponding to the preliminarydamper, between the rotary part connected to the driving shaft and therotary part connected to the driven shaft.

These friction devices are generally in the vicinity of the hub, in aspace left free around the latter, delimited circumferentially byelastic damping means.

Also housed in this space is the sub-assembly for preliminary torsionaldamping.

It is thus complicated to install in this space other active devicessuch as, for example, devices for damping the end-of-travel impacts ofthe means of meshing with clearance.

SUMMARY OF THE INVENTION

The present invention relates to a device notably enabling this drawbackto be eliminated.

To this end a novel torsion damping device is proposed, notably for theclutch of a motor vehicle, having two coaxial parts mounted rotatably inrelation to one another, counter to elastic damping means interposedcircumferentially between them, and an axially acting friction device,the latter comprising a friction washer subjected to the axial action ofelastic loading means, characterised in that the friction washer is ofsubstantially annular shape, and has a large internal diameter, so as toact radially beyond the elastic damping means, and in that the frictionwasher is slidably mounted on connecting braces between two washersguiding one of the rotary parts so that it is immobilised in rotation inrelation to the latter.

In this way, the space occupied by the friction washer and by thecorresponding elastic loading means is made free in the zone delimitedby the hub on the one hand and the elastic damping means on the other.

This free space can be used to advantage, for example for installing,radially inside the friction washer, a slide washer and its own load, aswill be explained further in the detailed description which is given byway of example.

It will be appreciated that the guiding washers are unaltered.

According to another aspect of the present invention, taking intoaccount the mounting of the friction washer on the braces, the elasticloading means for the friction washer consist of elastic lugs cut out ofthe washer. The necessity of disposing an elastic washer, such as aBelleville washer, adapted to act axially on the friction washer, as isthe case with the damping devices cited above, is thus avoided. There isthus a reduction in the number of parts.

Other characteristics and advantages of the invention will also emergefrom the description which follows by way of example, with reference tothe drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial view in section of a torsion damping deviceaccording to the invention;

FIG. 2 is a view in section of a central part of FIG. 1, along the lineII--II, with local cut-aways;

FIG. 3 is a perspective view of a friction washer participating in thetorsion damping device according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

These figures illustrate by way of example the application of theinvention to a torsion damping device which, designed to form a frictionclutch for the clutch of a motor vehicle, has, successively mountedrotatably two by two in relation to each other, three coaxial parts,namely a part A, consisting essentially of a hub 10, a part B,consisting essentially of a hub disc 11, which surrounds the hub 10, anda part C, consisting essentially of two guiding washers 12A and 12B,disposed on either side of the hub disc and surrounding the hub 10,joined one to the other by braces 9 of axial orientation and thus havingthe same rotational movement.

The coaxial part C has a friction disc 13, whose friction linings aredesigned, in a known manner, to be gripped between two plates of aclutch connected in rotation to a driving shaft, the output shaft of theengine in the case of a motor vehicle.

The hub 10 for its part has internal flutes 14, designed to join it to adriven shaft in rotation, the input shaft of the associated gearbox inthe case of such a motor vehicle.

The disc 11 is provided on its external periphery with notches 56, opentowards the outside and extending circumferentially, adapted to allowthe passage of the braces 9 with circumferential clearance.

The coaxial parts B and C are mounted rotatably in relation to oneanother, counter to elastic means interposed circumferentially betweenthem.

These elastic means consist, in the embodiment depicted, of pairs ofsprings 15, 15a of the helical spring type, the springs 15a beingsituated on the inside of the springs 15. More precisely, several pairsof springs 15 and 15a are evenly distributed about the axis of rotationof the parts B and C, extending along tangents to one and the samecircle centred about this axis.

In a manner well known per se, each pair of springs 15, 15a is mountedin apertures 50, 51 produced opposite one another in the disc 11 and theguiding washers 12A and 12B.

The assembly formed by the coaxial parts B, C and the groups of springs15, 15a constitutes the principal damping device of the friction clutch.

Its mode of operation, which is well known, will not be described infurther detail and is not the concern of the present invention.

The coaxial parts A and B are also mounted rotatably in relation to oneanother, counter to elastic preliminary damping means, within the limitsof an angular movement determined by the means of meshing with clearance16.

In practice, the hub 10 has on a longitudinal portion 17 of its externalperiphery radial projections 18 forming a male toothing. The hub disc 11for its part has on its internal periphery, opposite the portion 17 ofthe hub 10, notches 19, of angular aperture greater than those of thehub teeth, thus forming a female toothing, here of trapezoidal shapelike the complementary male toothing 18. A tooth 18 is engaged withcircumferential clearance in each notch 19, the possible angularmovement between the coaxial parts A and B thus being limited by theabutment of the teeth 18 of the hub 10 with the corresponding sides ofthe notches 19 in the disc 11. These teeth and notches thus form theaforementioned means of meshing with clearance 16.

The device is completed by a sub-assembly for preliminary dampingcomprising notably a preliminary damping cartridge of a known typearranged between the hub disc 11 and the hub 10.

As can be seen in FIG. 1, this cartridge, with the same axis as therotary parts A, B and C, is housed by virtue of a free space 55 situatedradially between the hub 10 and the pairs of springs 15, 15a. Axially,this cartridge is situated in the part of the free space 55 situatedbetween the disc 11 and the guiding washer 12A.

It consists of a secondary disc 40 joined to the hub by crimping, andtwo flanges 31 and 32 situated on either side of the secondary disc 40and connected to the hub disc 11 by fingers 33. More precisely, thesefingers 33, which, projecting from the metal flange 31, allow, bysnapping-in, a connection between the two flanges 31, 32, are engaged inopenings 34 in the hub disc 11 so that the flanges 31 and 32 are rotatedwith the hub disc 11. Circumferentially acting elastic preliminarydamping means 35, in practice springs of lower stiffness than thesprings 15, 15a, are interposed between the flanges 31, 32 on the onehand and the secondary disc 40 on the other hand, in a conventionalarrangement. They are thus forced elastically by a relative rotation ofthe hub disc 11 and of the hub 10 and tend to oppose this rotation. Afriction washer can be interposed between the preliminary dampingcartridge and the hub disc 11.

The operation of such a preliminary damping cartridge is known per seand will not be described in more detail.

As a matter of interest, it is pointed out that in a first phase thepreliminary damping springs 35 are compressed, the guiding washers 12A,12B and the disc 11 forming a rigid assembly by means of the stifferpairs of damping springs 15, 15a, this movement continuing until theclearance of the means of meshing with clearance 16 is eliminated.Thereafter the preliminary damping springs 35 remain stretched and arelative movement occurs between the disc 11 and the guiding washerswith the action of the pairs of damping springs 15, 15a.

According to an important characteristic of the invention, the torsiondamping device also comprises a friction device acting axially betweenthe coaxial rotary assemblies B and C, acting in parallel with theelastic damping means.

This friction device comprises a washer 60, depicted alone in FIG. 3.

This friction washer 60, in this case metallic, is of substantiallyannular shape with a large internal diameter. More precisely, itcomprises an active part of annular shape with, extending towards theinside, radial arms 61 forming means of connection with the connectionbraces 9 between the guiding washers 12A and 12B.

In practice, each radial arm 61, of rounded shape, has a bore 62 adaptedto be passed through by a brace 9, as can be seen in FIG. 1.

Thus connected to the braces 9, the washer 60 is held centred andimmobilised in rotation in relation to the rotary assembly C. It can,however, move axially by sliding along the braces 9.

As can be seen clearly in FIG. 1, the internal diameter of the washer 60is sufficiently large that its active part is situated radially beyondthe pairs of springs 15, 15a. It therefore acts in the vicinity of theexternal periphery of the hub disc 11.

The washer is positioned axially between the disc 11, against which itsactive part is in contact, and the guiding washer 12B.

On the active part of this washer are cut lugs 63 of rectangular shape.Each of these lugs extends approximately circumferentially from a radialside 64 connecting with the active part of the washer. These lugs act atregular intervals all around the washer, in pairs disposed back to back,that is to say their sides 64 being situated facing one another.

Advantageously, and as depicted in FIG. 3, one pair of lugs 63 acts ineach quarter of the washer extending between two braces 9.

These lugs are shaped so as to be inclined towards the guiding washer12B. Since their ends bear on the inner surface of the guiding washer12B, radially beyond the apertures 51, these lugs form elastic loadingmeans adapted to axially force the friction washer 60 against the disc11 and to grip the cartridge between the guiding washer 12A and thedisc.

In the plane of the washer 60, radially to the inside of the latter, inthe free space 55 between the hub 10 and the springs 15, 15a, isinstalled a washer for damping the end-of-travel impact 20 said slidewasher, coaxial to the hub disc 11 and placed against the latter on theside opposite the preliminary damping cartridge.

This slide washer 20 has on its inner circumference a female toothing 23facing the teeth 18 of the male toothing on the hub 10, analogous tothat on the hub disc 11 but having notches 23 narrower than the notches19 formed on the hub disc 11. One tooth 18 of the hub 10 is engaged ineach notch 23 of the slide washer 20, forming a means of meshing withclearance between the slide washer and the said hub 10.

The slide washer 20 is forced axially against the surface of the disc 11by an axially acting elastic loading means comprising a Bellevillewasher 22, interposed under stress between the guiding washer 12B and anapplication washer 21, fixed in rotation on the washer 12B by pinsengaged in holes in the latter.

Thus loaded, the slide washer 20 is adapted to rub against the disc 11.

When the hub disc 11 and the hub 10 have an angular movement of inrelation to one another, the teeth 18 move in the notches 19 and 23. Thenotches 23 being narrower than the notches 19, contact between the teeth18 on the hub 10 and the notches 23 occurs before the engagement betweenthe teeth 18 and the edges of the notches 19.

The washer 20, immobilised in relation to the hub 10, then rubs againstthe disc 11, braking the angular movement of the latter in relation tothe said hub.

In this way, the force of the impact of the teeth 18 against the edgesof the notches 19 in the disc 11 can be reduced.

The parameters determining the braking obtained by this slide washer,that is to say the coefficient of friction of the slide washer 20 andits load, in practice determined by the choice of the elastic washer 22,can be controlled independently of the friction device 60 acting betweenthe coaxial assemblies B and C.

In the example embodiment depicted in FIG. 1, a friction device actingin parallel with the elastic preliminary damping means is installedradially to the inside of the loading means 21 and 22 of the slidewasher 20.

This device comprises a friction washer 25 which, fixed in rotation onthe guiding washer 12B by pins engaged in holes in the latter, is forcedaxially against the hub 10 by a Belleville washer 26 interposed understress between it and the said guiding washer 12B.

A cone bearing 45, connected in rotation to the guiding washer 12A bypins engaged in holes in the latter, is interposed radially between theguiding washer 12A and a conical surface of the hub 10. Axially, thisbearing 45 is interposed between the guiding washer 12 and the flange31. The bearing 45 thus permits a centring of the guiding washers 12A,12B in relation to the hub 10 whilst preventing metal-to-metal frictionbetween the flange 31 and the guiding washer 12A.

Naturally, the disc 13 can be devoid of friction linings and be fixeddirectly to a plate fixed to the crankshaft of the vehicle.

The cartridge can be fitted with flanges 30, 31 made from plastic.

Finally, the limitation of the relative angular movement between thedisc 13 and the assembly formed by the hub 17 and the disc 11 can beachieved by means of contiguous turns of the springs 15, 15a. In thiscase, the braces 9 can then extend radially beyond the disc. Theconnection means 61 for the washer 60 will then be radially offsettowards the outside in relation to the active part of the washer.

In all cases, the active part of the washer 60 is located in thevicinity of the external periphery of the disc 11, so that higherfrictional torque is obtained.

This robust washer 60 is advantageously made from metallic material,given that a metal-to-metal contact is preferable with regard to thecoefficient of friction, but can also be made from fibre-reinforcedplastic.

I claim:
 1. A torsion damping device having two coaxial parts (B and C)mounted rotatably in relation to one another, counter to elastic dampingmeans (15, 15a) interposed circumferentially between them, and anaxially acting friction device, the latter comprising a friction washer(60) subjected to the axial action of elastic loading means (63),characterised in that said friction washer is of substantially annularshape, and has an internal diameter, so as to act radially beyond theelastic damping means (15, 15a) by means of an active part, and in thatthe friction washer (60) is slidably mounted on connecting braces (9)between two washers (12A, 12B) guiding one of the rotary parts (C) sothat it is immobilized in rotation in relation to the latter and theelastic loading means (63) for the friction washer (60) compriseselastic lugs cut out of the washer.
 2. The torsion damping deviceaccording to claim 1, wherein the friction washer (60) is provided withmeans (61) of connecting with the braces (9), offset radially inrelation to the active part of this washer.
 3. The torsion dampingdevice according to claim 1, wherein a toothed slide washer (20) isinstalled in the plane of the friction washer (60), radially to theinside of the latter.
 4. The torsion damping device according to claim3, wherein the device further comprises, mounted rotatably andcoaxially, a hub (10) and a hub disc (11) together with the coupledguiding washers (12A and 12B), the elastic preliminary damping means(35) being interposed between the hub and the disc, and the elasticpreliminary damping means are situated axially between the disc (11) andone of the guiding washers (12A), whilst the toothed slide washer issituated axially between the disc and the other guiding washer (12B),elastic loading means (21, 22) for the slide washer (60) bearing againstthe latter.
 5. The torsion damping device according to claim 4, thedevice further comprises a friction device (25, 26) associated with thepreliminary damper, the friction device being situated radially to theinside of the elastic loading means (21, 22) for the slide washer (60).